The present invention relates to a storage control device and to a storage system.
Since a storage control device is a computer device which employs a micro computer, sometimes it becomes necessary to update its program. It is possible to update the program simply if it is possible temporarily to stop access requests from a host computers (hereinafter termed “hosts”). However, sometimes it is the case that it is not possible to stop the storage control device, in order to obtain continuous 24-hour 365-day operation therefrom.
Thus, a technique has been proposed (in Japanese Patent Laid-Open Publication 2005-242574) for updating of a program within the storage control device, with which there is no necessity to stop the flow of access requests from the hosts; in other words, there is no requirement to stop the operation of the storage control device.
With the technique described in this prior art document, a cluster structure is employed, and redundant paths are established between the hosts and the storage control device. Due to this, the program of one cluster is updated after failover from that one cluster to another cluster. Accordingly, with this prior art method, it is possible to update the program without stopping the storage control device.
However, with this prior art method, it is necessary to set redundant paths between the hosts and the storage control device, to provide a cluster structure in the storage control device, and to implement path control software and so on on the hosts in order to change over from the normal paths to the redundant paths. Due to this, the structure becomes more complicated, and the cost also increases.